"Even if the formulary is identical, the microenvironment, which controls the nuances, isn't identical."
Agreed. In addition, however, the formulary for Guinness draught is far from identical, for, as I have read, there are 19 different recipes for it throughout the world, each tailored to a particular region's tastes, as they see it (more sweetness, tweaked malt, hyped bitter notes).
Of course, I'm of the opinion that local beer is always better, and reflective of the region's tastes in small but descriminate ways.
Geary's India Pale Ale in Portland, ME? A mite more laid-back than the Burning River IPA from Great Lakes in Cleveland. 'Tis a bitter brew they like in my native northeast Rustbelt Ohio.